Amino-containing Siloxane Coupling Agent Modification Method
Aug 9, 2023
The application of silane coupling agent in polyurethane adhesive is to add a silane coupling agent containing active end group -OH or -N pressure to the polyurethane prepolymer with terminal NCO group, or add a silane coupling agent with terminal OH group to the polyurethane prepolymer with terminal OH group. Add an organosilane coupling agent containing NCO groups. In this way, the NCO-terminated or OH-terminated polyurethane prepolymer is modified into a silicon ester-terminated prepolymer.
Therefore, in order for polysiloxane to react with diisophenolate, the siloxane molecular chain must contain active groups that react with CO groups, such as hydroxyl and amino groups. However, since the active matrix directly connected to the silicon atom is difficult to react with the isocyanate, the two can be connected through an alkyl chain to improve the reactivity of the matrix.
In polysiloxane-modified polyurethane copolymers, the solubility parameters of the polysiloxane in the soft segment and the carbamate or hydroxyl bond in the hard segment are quite different. Therefore, in the synthesis of such copolymers, the choice of solvent is very important. Pivotal. Generally, polar and non-polar mixed solvents are used in the addition polymerization process. The mixed solvents used are: dioxane/tetrahydrofuran (DOX/THF), N,N'-methylformamide/dimethylmethylene Inkstone (DMF/DMSO), etc.
Introducing polar groups such as beryl ethyl and chloropropyl groups into the organic silicon oligomer chain segment can improve its solubility in polar solvents. Therefore, a single solvent such as N,N'-dimethylacetamide can be used in the synthesis reaction. Studies have shown that when synthesizing silicone-modified polyurethane, the solvent has a great influence on the average molecular weight of the product. A product with high molecular weight of soft segment and hard segment can be synthesized by using a single solvent, but the introduction of polar groups destroys the regularity of the soft segment structure, which will have an adverse effect on the mechanical properties of the modified polyurethane.
A silicone modified waterborne polyurethane was synthesized with APTMS (Polytetrahydrofuran glycol) and IPDI (3-aminopropyl Trimethylsilane), As the content increases, the swelling of water and solvent decreases, while the swelling of ethylene solvent increases. The modified solution stabilizes for up to 6 months.
The polydimethylsiloxane (CPDMS) with active end groups (- OH, - NH2) is used to synthesize organosilicon modified polyurethane through addition polymerization and Chain reaction with isophoric acid terminated compounds or prepolymers. The hydrolysis resistance of organic silicon modified polyurethane was improved by reacting single-ended tibial or amino PDMS (M0=2000g/mol) with polyurethane prepolymer.
In addition, a muscle embedding comparison experiment was conducted on PDMS modified polycarbonate polyurethane for 18 months, and it was found that PU without PDMS modification exhibited network like long cracks on scanning electron microscopy (XlOO), while PU modified with PDMS only had some round holes. A waterborne cationic polyurethane lotion that can be self crosslinked and stabilized at room temperature was synthesized with aminoethyl triethoxysilane. After modification, due to the hydrolysis and cross-linking of siloxane, the heat resistance was improved, and the organosilicon participated in polymerization and cross-linking, forming a relatively uniform phase, and the phase separation was not obvious, so that the cationic waterborne polyurethane modified by organosilicon had a glass transition temperature.
Silicone-derived water-based photosensitive polyurethane was synthesized, and the effects of two photo-crosslinking monomers, methyl cellulose ethyl ester (HEMA) and oxidized cellulose ester (EA), on the water resistance and structure of the cured film were synthesized. At the same time, organic silicon coupling agent and photopolymerization material are added to improve the ability and transparency of the polyurethane surface.
Using MDI (4,4'-diphenylmethane diisoneunate), PBA (polyethylene glycol 1,4-butylene ethylene glycol), PDMSCBY-853) as raw materials, synthesized under normal temperature and humidity Cross-linked and condensed polyurethane materials, the effects of different ratios of Y-AMS (3 aminopropyl-methyltriethoxysilane) and APS (aniline-methyltriethoxysilane) on the mechanical properties of the material were investigated. It is found that the contact angle of the material increases, the glass transition temperature increases, the strength of the material increases, and the elongation decreases. Due to the existence of the siloxane chain, the originally unified urethane hydrogen bond is destroyed, the crystal structure of the material becomes smaller than before modification.
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